A conventional diode includes a p-type phase change material (e.g. germanium-antimony-tellurium (Ge—Sb—Te)) disposed on an n-type semiconductor (e.g. n-silicon). The p-type phase change material contains positive charge carriers (holes) while the n-type semiconductor contains negative charge carriers (electrons). The terminals of the conventional diode are attached to each of the p-type phase change material and the n-type semiconductor. A boundary between the p-type phase change material and the n-type semiconductor is called a p-n junction, where the action of the diode takes place. Current flows in a direction from the p-type side (anode) to the n-type side (cathode). The phase change material acts as a data storage layer which is capable of switching between crystalline and amorphous states. The phase change material in the crystalline and amorphous states has different electrical resistivity. Data can be stored based on the different electrical resistivity of the phase change material in the crystalline and amorphous states.
High reverse breakdown voltage and low leakage current are desired for a diode used in a memory device. However, the conventional phase change p-n junction diode has low reverse breakdown voltage and high leakage current which is detrimental to a read operation of the memory device.